Doctor wasn't exactly clear on how to use new needle, pls help!

So basically, my injection needle was 23g and 1 inch long.. For SubQ.. Yeah.. My doctor used to tell me to stick it in halfway instead of all the way, so ofc, I used to do that. However, my new needles that I requested were 25g and 5/8 of an inch, so like a standard SubQ needle. Before getting these prescribed, he told me I was going way to shallow since there was always a bump after my injections. With these new needles, I'm kind of scared to go all the way in but I'm thinking maybe I should?? I still have the same big lump after injecting.

TLDR; How deep are you actually meant to stick SubQ needles in? Google says all the way but I don't know if that holds true for testosterone